WO2020088692A1

WO2020088692A1 - Method for enhancing electrostatic discharge performance

Info

Publication number: WO2020088692A1
Application number: PCT/CN2019/116838
Authority: WO
Inventors: 陈斯伟; 张坤
Original assignee: 晶晨半导体(上海)股份有限公司
Priority date: 2018-10-29
Filing date: 2019-11-08
Publication date: 2020-05-07
Also published as: CN109481841A

Abstract

A method for enhancing electrostatic discharge performance, applicable in touch key circuits. The method particularly comprises the following steps: step S1, eliminating all electrostatic impedance elements (1) in a touch key circuit; and step S2, after the electrostatic impedance elements (1) are eliminated, providing an anti-static rubber on a touch key (2) in the touch key circuit. The invention eliminates the electrostatic impedance element (1) from the touch key circuit, and provides the anti-static rubber on the touch key (2), thereby effectively reducing a voltage difference caused by conductivity of an electrostatic impedance element (1), and fully blocking a radiation signal of the electrostatic impedance element (1) without affecting sensitivity. The solution for touch key circuits is stable, and has a low circuit cost.

Description

A method to improve electrostatic discharge performance

Technical field

The present invention relates to the field of semiconductor technology, and in particular to a method for improving electrostatic discharge performance in a touch key circuit.

Background technique

At present, many electronic products use the touch key mode, and there is a gap between the circuit board pad of the touch key and the structure of the electronic product, making the electrostatic discharge performance more and more difficult. The basic requirements for electrostatic discharge in this technical field are: contact discharge 4KV, air discharge 8KV, test standards and methods comply with IEC61000-4-2, choose CLASS A standard, in which there is no change in function, especially touch the circuit board pad of the button There is a gap with the product structure, and the touch chip is directly damaged by air discharge, and the electrostatic impedance element cannot meet the basic requirements in the field.

In the prior art, as shown in FIG. 1, all touch key circuit board pads, chip power supplies, and control signal lines in the touch key circuit need to add electrostatic impedance components to meet the electrostatic discharge performance, and block the touch key circuit structure and The gap between the pads of the touch button circuit board meets the electrostatic discharge performance. The above two methods will affect the touch sensitivity of the touch button, making the user experience poor, the electrostatic discharge performance unstable, and the circuit cost relatively high.

Summary of the invention

In view of the above problems in the prior art, a method for improving the electrostatic discharge performance is now provided.

The specific technical solutions are as follows:

A method for improving the performance of electrostatic discharge is used in a touch key circuit, which specifically includes the following steps:

Step S1: Remove all the static impedance elements in the touch key circuit;

Step S2: After removing the electrostatic impedance element, install anti-static glue on the touch buttons in the touch button circuit.

Preferably, in the step S1, the electrostatic impedance element including the circuit board pad, the touch sensing control power supply and the control signal line is removed from the touch key.

Preferably, after the step S2, when the touch button is not touched, it has a first capacitance.

Preferably, the first capacitance includes a reference capacitance of the circuit board pad, a polar plate capacitance between the circuit board pad and the surrounding copper plate.

Preferably, after the step S2, when the touch button is touched, it also has a second capacitor and the first capacitor.

Preferably, the second capacitor is a contact capacitor.

Preferably, the first capacitor and the second capacitor are connected in parallel.

Preferably, the change rate of the capacitance before and after the touch button is:

C% = C _f / C _Px + C _Py ;

C% is used to indicate the rate of change in capacitance before and after the touch of the touch button;

C _{f is} used to represent the capacitance value of the second capacitor;

C _{Px is} used to represent the capacitance value of the reference capacitance of the circuit board pad;

C _{Py is} used to indicate the capacitance value between the circuit board pad and the surrounding copper plate.

The beneficial effects of the technical solution of the present invention are: by removing the static impedance element in the touch key circuit, and providing anti-static glue on the touch key, the voltage difference caused by the conduction of the static impedance element can be effectively reduced and the radiation signal of the static impedance element can be completely blocked. And the sensitivity has no effect, the scheme of the touch key circuit is stable and the circuit cost is low.

BRIEF DESCRIPTION

With reference to the accompanying drawings, the embodiments of the present invention will be described more fully. However, the attached drawings are only for illustration and explanation, and do not constitute a limitation on the scope of the present invention.

FIG. 1 is a distribution diagram of electrostatic impedance elements in the entire touch key circuit diagram in the prior art;

2 is a flowchart of a method for improving electrostatic discharge performance according to an embodiment of the present invention;

FIG. 3 is a circuit diagram when the touch button of the embodiment of the present invention is not touched;

FIG. 4 is a circuit diagram when a touch key of an embodiment of the present invention is touched.

detailed description

The technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

The present invention will be further described below with reference to the drawings and specific embodiments, but it is not intended to limit the present invention.

In the prior art, as shown in FIG. 1, the touch button 2 includes a circuit board pad, a touch-sensing control power supply, and a control signal line. It is necessary to add an electrostatic impedance element 1 to meet the electrostatic discharge performance, and block the touch button 2 and The gap between the pads of the touch button circuit board meets the electrostatic discharge performance. The above two methods will affect the touch sensitivity of the touch button 2, making the user experience poor, the electrostatic discharge performance unstable, and the circuit cost relatively high.

In view of the above-mentioned problems in the prior art, the present invention provides a method for improving the electrostatic discharge performance, which is used in a touch key circuit, and specifically includes the following steps:

Step S1: Remove all the static impedance elements 1 in the touch key circuit;

Step S2: After removing the electrostatic impedance element 1, an antistatic glue is provided on the touch button 2 in the touch button circuit.

Through the technical solution of the above method for improving the electrostatic discharge performance, as shown in FIG. 2, it is used in the touch key circuit, and the electrostatic impedance element 1 has a pF-level junction capacitance, which has the sensitivity to the touch key 2 for the sensitive signal of the touch key circuit. It has a great impact, so first remove the electrostatic impedance element 1 in the touch key circuit, which can save costs, and then install anti-static glue on the touch button 2 to effectively reduce the voltage difference generated by the electrostatic impedance element 1 conduction and completely block the electrostatic impedance element 1 radiates a signal, and without affecting the sensitivity of the touch button 2, the scheme of the touch button circuit is stable.

In a preferred embodiment, in step S1, the static impedance element 1 including the circuit board pad, the touch sensing control power supply and the control signal line in the touch key 2 is removed.

Specifically, in the prior art, the touch button 2 includes a circuit board pad, a touch-sensing control power supply, and a control signal line. It is necessary to add an electrostatic impedance element 1 to satisfy the electrostatic discharge performance, as shown in FIG. 1, which makes the entire touch The cost of the key circuit is increased. In view of the above problems, this embodiment removes the touch panel 2 including the circuit board pad, the touch-sensing control power supply, and the electrostatic impedance element 1 on the control signal line, without affecting the sensitivity of the touch panel 2, The circuit cost is further reduced.

In a preferred embodiment, after step S2, when the touch button 2 is not touched, it has a first capacitor;

The first capacitance includes the reference capacitance of the circuit board pad and the capacitance of the plate between the circuit board pad and the surrounding copper plate;

After step S2, when the touch button 2 is touched, it also has a second capacitor and a first capacitor;

The first capacitor is connected in parallel with the second capacitor;

The change rate of the capacitance before and after the touch of the touch button 2 is:

C% = C _f / C _Px + C _Py ;

C% is used to indicate the rate of change in capacitance before and after the touch of the touch button 2;

C _{f is} used to represent the capacitance value of the second capacitor;

C _{Py is} used to indicate the capacitance between the circuit board pad and the surrounding copper plate.

Specifically, a capacitor formed by sandwiching an insulator between the two plates; for the touch button 2, the metal sensor pad on the circuit board pad of the touch button 2 serves as a plate of the capacitor, and the surrounding metal copper or The finger serves as the other polar plate, the material of the pad of the touch key circuit board itself or the medium covered on the pad of the touch key circuit board serves as an insulator in the middle of the capacitor, and finally constitutes the capacitor.

Further, as shown in FIG. 3, when the touch button 2 is not touched, it has a first capacitance, where the first capacitance includes the reference capacitance C _Px of the circuit board pad and the capacitance C _Py between the circuit board pad and the surrounding copper plate As shown in FIG. 4, when the touch button 2 is touched, it has both a second capacitor and a first capacitor, where the second capacitor is the contact capacitor C _f .

Further, since the first capacitor and the second capacitor are connected in parallel, the change rate of the capacitance before and after the finger touches the touch button 2 is: C% = C _f / C _Px + C _Py ; where C% is used to represent the touch button 2 The change rate of the capacitance before and after the contact; C _{f is} used to indicate the capacitance of the second capacitor; C _{Px is} used to indicate the capacitance of the reference capacitor of the circuit board pad; C _{Py is} used to indicate the relationship between the circuit board pad and the surrounding copper plate The capacitance value between.

Further, an experimental comparison is made between the existing technology and the improved electrostatic discharge performance of this embodiment, and the following conclusions are drawn. To test the electrostatic discharge performance of the power port of the touch chip, the test standards and methods are in accordance with IEC61000-4-2, select CLASS A standard, where there is no change in function. For the original design and assembly of several electrostatic impedance components 1, it is concluded that the voltage when the touch button 2 is touched is between 3KV-5KV, and the voltage when the touch button 2 is not touched is In this embodiment, the voltage when the touch button 2 is touched is between 3KV-5KV, and the voltage when the touch button 2 is not touched is between 7KV-9KV. There is no margin for the test result of the electrostatic discharge performance of the technical solution originally designed and assembled with several electrostatic impedance elements 1, while the test result for the electrostatic discharge performance of the technical solution with the addition of anti-static glue is sufficient, which has no effect on the sensitivity of the touch button 2. Further, by removing the electrostatic impedance element 1 in the touch key circuit, and setting an antistatic glue on the touch button 2, the voltage difference generated by the conduction of the electrostatic impedance element 1 is effectively reduced and the radiation signal of the electrostatic impedance element 1 is completely blocked, and the sensitivity No effect and the scheme of touch key circuit is stable.

At the same time, it is known from the comparison results of the circuit cost analysis that the technical solution for adding anti-static glue is cheaper than the original technical solution for designing and assembling several static impedance components 1, so it is suitable for popularization and use and improve the user's experience.

Further, by removing the electrostatic impedance element 1 in the touch key circuit, and setting an antistatic glue on the touch button 2, the voltage difference generated by the conduction of the electrostatic impedance element 1 is effectively reduced and the radiation signal of the electrostatic impedance element 1 is completely blocked, and the sensitivity No effect, the scheme of the touch key circuit is stable and the circuit cost is low.

The above is only a preferred embodiment of the present invention, and therefore does not limit the implementation and protection scope of the present invention. Those skilled in the art should be able to realize the equivalence made by using the description and illustration content of the present invention. The solutions obtained by replacement and obvious changes should be included in the protection scope of the present invention.

Claims

A method for improving electrostatic discharge performance, which is used in a touch key circuit, is characterized by specifically including the following steps:

Step S1: Remove all the static impedance elements in the touch key circuit;

Step S2: After removing the electrostatic impedance element, install anti-static glue on the touch buttons in the touch button circuit.
The method for improving the electrostatic discharge performance of a touch button according to claim 1, wherein in the step S1, removing the touch buttons including circuit board pads, touch sensing control power supply and control signal lines The electrostatic impedance element.
The method for improving the electrostatic discharge performance of a touch key according to claim 2, wherein after the step S2, when the touch key is not touched, it has a first capacitance.
The method for improving the electrostatic discharge performance of a touch button according to claim 3, wherein the first capacitor includes a reference capacitance of the circuit board pad, a pole between the circuit board pad and the surrounding copper plate Board capacitance.
The method for improving the electrostatic discharge performance of a touch key according to claim 4, wherein after the step S2, when the touch key is touched, it also has a second capacitor and the first capacitor.
The method for improving the electrostatic discharge performance of a touch button according to claim 5, wherein the second capacitor is a contact capacitor.
The method for improving the electrostatic discharge performance of a touch button according to claim 5, wherein the first capacitor and the second capacitor are connected in parallel.
The method for improving the electrostatic discharge performance of a touch button according to claim 5, wherein the rate of change in capacitance before and after the touch button is contacted is:

C% = C f / C Px + C Py ;

C% is used to indicate the rate of change in capacitance before and after the touch of the touch button;

C f is used to represent the capacitance value of the second capacitor;

C Px is used to represent the capacitance value of the reference capacitance of the circuit board pad;

C Py is used to indicate the capacitance value between the circuit board pad and the surrounding copper plate.